Mixer means and impeller therefor



' Dec. 6, 1966 Filed Jan. 8, 1965 J. J. LENNON ETAL MIXER MEANS AND IMPELLER THEREFOR 2 Sheets-Sheet 1 INVENTORS' JOHN J. LENNON VlCTOR M. MACNULTY P WWW. q w

ATTORNEYS 1966 J. J. LENNON ETAL 3,290,016

MIXER MEANS AND IMPELLER THEREFOR 2 Sheets-Sheet 2 INVENTORS JOHN J. LENNO N BY VICTOR M. MACNULTY Rm, MM; W

FIG?) ATTOR NEYS United States Patent 7 Claims. (Cl. 259-408) This invention relates to material processing, and more particularly to an improved equipment or apparatus for mixing or dispersing materials as in the manufacture of paint, food, paper, and the like. The apparatus here concerned is applicable generally to the disseminating of solids in liquids and semi-liquids. including viscous volumes with the solids being disintegrated and dispersed for suspenson or dissolving in the liquids.

The'invention provides an improved mixer or disperser for such material processing, and for said disperser a shearing impeller of novel design and'efficient operation.

The invention will be understood from the following description taken in conjunction with the accompanying drawings in which FIG. 1 is a side elevation of the invention dispersing apparatus, with the material container cut away to show the impeller therefor;

FIG. 2 is a horizontal section through the impeller shaft along the line 22 of FIG. 1 and showing the impeller in top plan;

FIG. 3 is a perspective view of a compressor unit of the impeller, as viewed at the front of the impeller disc, moving from right to left; and

FIG. 4 is a like view from the opposite side of the impeller compressor unit as seen at the rear of the disc, moving from left to right.

The invention disperser comprises a generally cylindrical vat, tub or like container or tank in which a varying volume or batch of the generally viscous material may be desposited or contained for the processing. The material container is preferably fabricated from a material which is substantially impervious to the substances to be processed, and which may be, for example, stainless steel. The disperser tank will generally have vertical sides walls 11, and is herein formed for complete efiicient mixing also with top and bottom walls having annular dished portions 12, 13 inclined downwardly and upwardly, from central lateral portions 14, 15, and merging'smoothly, or through a gradual curve, with said vertical side walls 11. The tank 10 may be fitted for stationary mounting on legs or the like supports such as are conventional and therefore not shown, and it will be provided also with filling and emptying openings and demountable closures for the same, again such as are conventionally employed and not a part of the invention.

The invention disperser comprises further an electric or other impeller drive motor M supported on a lateral arm of bracket 17 carried in turn on a hollow frame or shaft housing 18 centered over and rigidly fixed to the tank 10. The housing 18 also mounts a cover or casing 19 housing a gear train or other suitable means by which the horizontal motor drive shaft 20 is coupled to the vertical impeller drive shaft 21, for driving of the latter by the motor M at desired impeller speed and directly or through variable speed or other suitable form of transmission. The impeller drive shaft has suitable bearing support in the casing 19, extends through the housing 18 into the tank 10, has anoverall length to extend to the desired proximity to the bottom of the tank, and may be made up in sections or otherwise fitted for driving the impeller at various levels in the tank.

The impeller of the invention comprises an annular, thick, transverse plate or disc 22, which may be stainless 3,290,016 Patented Dec. 6, 1966 steel, and which for rigid mounting and rotation with the shaft 21 is fitted with a hub 23 which may be welded or bolted to the disc 22 and be keyed to the shaft as through a collar or sleeve 230. As the tank 10 may be fashioned in different sizes to accommodate different material volumes, any particular disc 22 may be of a size having the desired proportional relation to the tank with which it is designed for use. For reasons connected with the operation of the compression units or vanes 24 to be described, at least an outer marginal zone of the impeller plate or disc 22 if formed of a stainless steel desirably is protectively treated as by appropriate coating or otherwise hardened against abrasive wear, at both faces in cases where both are equipped with the vanes 24.

In accordance with the invention, a balanced number or array of shear-promoting jet-flow creating compression units 24 are mounted near or proximate the periphery of and at one or the other or both sides of the disc 22, and each wholly inboard with reference to the plate edge. Each such unit comprises an upright or vertically extending blade or vane 25 rigidly fixed to the disc 22, as by an integral lateral lip or flange 26 which may be inturned from the vane 25 and welded to the disc. The vanes 25 of said units 24 are of a length circumferentially of the impeller plate calculated with reference to the size thereof and number of units, and have maximum height at the leading ends and slope toward the plate to a lesser height at the trailing or discharge ends.

Each compression unit 24 of the invention further comprises a shroud or overhang 27, which may as herein be an out-turned lip or flange of the vane 25, mounted at the upper margin of and to project laterally outward of the vane, and herein with one end extending substantially to but ending inboard of the periphery of the disc or plate 22. These shrouds 27 as shown extend the full length of the respective vanes 25, and have a lateral projection generally less than the length of the vanes 25, being in the illustrated example about equal to the height of the vanes at the low exit ends.

Each compression unit or more particularly the plane of the shaft-paralleling vane 25 thereof is oriented at a predetermined angle to the line or direction of compression unit travel or advance, which line or direction may be taken as that tangent to the disc 22 perpendicular to the radius drawn to the intersection or nearest approach of the shroud 27 with the disc periphery as indicated on FIG. 2 at the right where the angle concerned is marked B. This deviation angle B will be called the pumping angle. Again referring to FIG. 2, wherein a clockwise rotation is indicated for the impeller, the orientation of the compression unit vane at the pumping angle B is seen to place the leading edge of the vane inside and the trailing edge thereof outside an arc or perimeter drawn through the midpoint of the vane, with the vane as a whole being thus angled across and somewhat transverse to the relative impact line or travel path of the open leading end of each vane as it rapidly passes through the material upon rotation of the impeller. The action of the vane 25 accordingly is to deflect or laterally displace the material impinging on its inner leading surface towards or together with that striking its outer or trailing surface, thus in effect to accelerate or pump the mass outwardly as it passes over the active outfacing surface of the vane, in said rotary movement of the same. Said pumping angle B is selected with reference to impeller speeds, loads thereon and other operative factors and need not be large, efficient values generally being under rather than above 45 for most materials to be operated upon.

Still further in accordance with the invention, the shroud or overhang 27 of each vane is inclined or sloped rearwardly and herein vertically towards the adjacent fiat face of the plate 22, at a predetermined angle to the horizontal plane thereof. This rearwardly converging angle, noting particularly FIGS. 1, 3 and 4, will herein be termed the compression angle, and is designated as A on FIGS. 3 and 4. The inclining rearwardly of the shroud at a compression angle A lowers or reduces the height or spacing of the shroud from the plate face from the leading to the trailing edge of each vane and to a determined extend proportional to the compressive or ejector-like action desired for the given operating factors of speed, load and others including the materials to be acted upon.

From the description and illustrative views it is evident that the compression units 24 together with the respective portions of plate 22 vertically opposite the inclined shrouds 27 and adjoining the bases of the vanes 25 define three-sided or semi-closed channels or passages which are outwardly open along the circumferential or longitudinal area opposite the vanes 25. These passages, longitudinally considered, each has a relatively largeinlet or intake opening or port at the rotatively leading end and a relatively small outlet or discharge opening or ejection port at the trailing end. The ratio of the exit port or opening to that of the intake port or opening is determined with reference to the operative factors as above noted for most uses is of the order as herein shown by way of example.

A number of the compression units 24 are provided at both top and bottom sides of the plate 22, uniformly distributed around the same at the respective plate face and proximate to the periphery of the latter, but sufliciently angularly offset intermediately at the opposite faces of the plate. The compression unit positioning as herein shown in such as to have the outermost extremity of the shrouds 27 terminate at or within the peripheral edge of the disc or plate 22.

In the operation of the apparatus the impeller shaft 21 is rotated at relatively high speed to advance the compression'units 24, moving at the speed of the peripheral zone of the disc 22, rapidly through the material being processed. In each of the units 24, as thematerial enters the relatively large intake or inlet opening, it is deflected and directed outwardly, as already explained, and more particularly it is compressed toward the plate 22 and between the shroud 27 and the adjacent face portion of the plate toward which the shroud converges to form the much smaller outlet opening or discharge port for the compression unit. The material and more particularly the solids content thereof is thus accelerated in both lateral and vertical planes while subject to passage through the units, and is therefore delivered or discharged from the units in jet streams moving much more rapidly than the surrounding fluid medium. As will be appreciated by those skilled in the art, when such relatively high velocity discharge or jet streams impinge upon the relatively slow moving material external to the impeller device it will subject the material to an hydraulic shear of large magnitude, causing a highly efficient dissemination or dispersing of the material, and the desired improved breaking up or disintegrating of its solid content.

The positioning of the compression units is also such as to qualify them as operatively independent. That is, the spacing or interval between succeeding units 24 is at least that which allows each to perform its compressing and jet-like ejector shearing action on a different portion or flow of the material being processed, and with the discharge from each of the several units passing outwardly of or clear of the succeeding unit, as indicated by the dotdash flow lines at the lower left on FIG. 2. The number of compression units which may be' employed will thus vary with the size of the impeller plate and the proportioning of the compression units relative to it, the series of four compression units per plate sid'e herein indicated being merely exemplary, as for a relatively small diametered plate such as say 6 in. The proportions of the disc or plate 22 may be much larger in relation to the size and number of compression units, as in the previous example, there being as many as 11 or 12, or more units in some instances provided on each side of the plate.

A further feature of the invention is that the pluralities or sets of compression units on the opposite sides of the plate desirably are alternated or staggered, as shown in FIG. 2, whereby the discharge or shearing action of the units at one side of the disc is angularly offset with respect to the intake and compression action of the units on the other side of the plate.

The orientation of the compression units at a pumping angle to the direction of angular movement of any point on the disc 22 serves as already mentioned and along with the vertical compressing to accelerate the material passing the unit. The deflecting of the material from or outwardly of its flow path is observed also to produce a solids dispersal pattern spreading inwardly of an are extended from the trailing edge of the vane 25. Accordingly the configuration of the vane trailing edge may be variously ordered or arranged to differently influence the shearing action in this respect. For example one or more longitudinal slits 28, FIGS. 3 and 4, may be cut in the vane 24 from its trailing edge and forwardly for some fraction of its length, for example about one-third, with the result in effect of extending the length of the discharge surface or edge past which the material is accelerated.

In the course of test operation of the impeller apparatus of the invention various unforeseen specific advantages have been discovered. In the language of the mixing art the given material subject to the processing displaces or vortexes at substantially lower than usual rotary speeds of the impeller, generally not more than about half that needed with any impeller device heretofore available. Upon the occurrence of such vortexing the central area of the rotating impeller plate is exposed and left substantially bare of the mixture material which in effect whirls bodily with an attendant rolling action at the peripheral portion of the plate over a marginal area thereof having a radial inward extent in the operation of the herein disclosed impellers of about twice that of the circumferential zone in which the compressive shrouded vane units 24 are located. At the same time the compressive and jet-like discharge action at the vanes causes the suspended components, such as pigment particles in the case of paint mixtures, to act abrasively against each other and in effect to grind themselves, making for rapid complete dispersion of the suspended matter. This highshear compressive grinding action between the particles, even in the instances 'of such highly viscous materials as the epoxys, rapidly brings about a complete dispersion of the suspense material, in an importantly reduced operating time and within which generally no material particles are left of a size greater than about 5 microns. Such dispersal of the matter within the mixture is foundto be so thorough that any necessity for incorporating a suspending agent is obviated.

A further important beneficial effect is that our impeller apparatus makes it possible to obtain uniformity throughout the mixture mass as to color and tinting and to accomplish the same in a readily repeatable standardized fashion, a matter which has heretofore not satisfactorily been available as between successive batches.

Moreover all these advantages are obtained immediately in a one-step operation utilizing but the one batch tank or container equipped with our impeller device. This contrasts with the various rnulti-step procedures heretofore deemed necessary, such as that of the so-called sand milling in which special sands or silicates are introduced into the mixtures and subsequently attempted to be removed by screening, and in the course of which processing as many as seven successivecontainers receive the mixture materials, necessitating the cleaning of each of the number of containers, as contrasted with the single container which suffices for the practice of applicants invention.

Our invention both as to apparatus and method is not limited to the particular means and steps as herein illustrated and described by way of example, the scope thereof being pointed out in the appended claims.

We claim:

1. A shearing impeller for a dispersing apparatus comprising a generally circular plate, means mounting the plate transversely of and for rotation with an impeller shaft, centrally perpendicular thereto, and at least one compression unit, wholly inboard of the plate at the marginal zone thereof, said unit comprising a laterally projective vane in a plane paralleling the shaft axis and oriented at a pumping angle to the direction of rotation of the plate, and an overhanging shroud out-turned at right angles to the vane at the outer edge thereof and inclined at a compression angle to the plane of the plate, said shroud defining with said vane and the opposing region of the plate an elongate passage deviating from the direction of rotary movement and reducing from the inlet to the outlet, whereby the compression unit accelerates the ambient material to be mixed both by pumping and by compressing said material subject to said passage and causing it to discharge from the passage outlet at relatively high velocity and so as to impinge upon the encompassing material with a violet shear and augmented dispersing action.

2. The impeller of claim 1 wherein the inclined shroud comprises a generally rectangular flange member integral with the vane of the unit.

3. The impeller of claim 1 wherein the vane is oriented to place its leading edge inward and its trailing edge outward of the medial portion of the vane and whereby upon rotation of the impeller the outer face of the vane thrust outwardly against the material to be dispersed.

4. The impeller of claim 1 wherein a plurality of the compression units are uniformly distributed at operatively isolated spacings about the marginal zone of the plate.

5. The impeller of claim 1 wherein like pluralities of the compression units are provided at opposite faces of the plate and with the units of one face located at plate radii intermediate the radii of the units of the other plate face.

6. Disperser apparatus for processing materials such as paints and the like having ingredients requiring to be mixed, comprising an impeller shaft, means supporting said shaft for rotation about a vertical axis and with its lower end immersed in a volume of the material, a motor drive for the shaft, and a shearing impeller on said lower shaft end, said impeller having a transverse disc rigidly fixed to the shaft and a series of material compressing units distributed about the disc periphery, each said compression unit formed with a vertical portion on the disc inboard of the periphery thereof and oriented at a pumping angle to the direction of unit advance, and a lateral portion spaced from and overhanging the disc and inclined rearwardly and vertically at a compression angle to the plane of the disc, said vertical and lateral portions combining with the opposing portion of said disc to form a semiclosing reducing passage in moving through which the material is substantially accelerated to discharge therefrom as a relatively fast moving jet impinging on the ambient material with a violent shear and thereby dispersing the material with disintegration of the solids for dissolving or suspending in the vehicle thereof.

7. In anapparatus for the dispersive mixing of divisible solid matter with fluid and semi-fluid carrier vehicles in a confined mass, an impeller device comprising a rotary shaft having a free end and a driving end, a rigid circular plate centrally afiixed at the shafts free end, and a number of annularly spaced, shear-promoting jet-flow creating compression units on said plate, said compression units comprising upstanding vanes, said vanes oriented at a predetermined angle to the direction of compression unit advance, wlhereby upon rotation of said shaft said vanes outwardly pump said mass, and laterally projecting shrouds carried on said vanes, said shrouds located inboard of the edge of said plate and disposed at an angle inclined to the plane of the plate such that the spacing of the shrouds from the plate reduces from the leading to the trailing edges of the vanes, whereby upon rotation of said shaft said shrouds compress said mass towards said plate, said vanes and shrouds of said compression units thereby accelerating the material of said mass which passes therethrough in both lateral and vertical planes and discharging it in relatively high velocity jet streams that impinge upon the relatively slow-moving material external to the impeller device to subject that to hydraulic shear, and cause the desired dispersing of the material and breaking up of its solid content.

References Cited by the Examiner UNITED STATES PATENTS 2,692,127 10/1954 Conn 259-134 2,984,462 5/1961 OConnor 259107 3,044,750 7/1962 Sohmitt 259-434 FOREIGN PATENTS 1,297,805 5/ 1962 France.

749,327 5/ 1956 Great Britain.

WALTER A. SCHEEL, Primary Examiner,

R. W. JENKINS, Assistant Examiner, 

1. A SHEARING IMPELLER FOR A DISPENSING APPARATUS COMPRISING A GENERALLY CIRCULAR PLATE, MEANS MOUNTING THE PLATE TRANSVERSELY OF AND FOR ROTATION WITH AN IMPELLER SHAFT, CENTRALLY PERPENDICULAR THERETO, AND AT LEAST ONE COMPRESSION UNIT, WHOLLY INBOARD OF THE PLATE AT THE MARGINAL ZONE THEREOF, SAID UNIT COMPRISING A LATERALLY PROJECTIVE VANE IN A PLANE PARALLELING THE SHAFT AXIS AND ORIENTED AT A PUMPING ANGLE TO THE DIRECTION OF ROTATION OF THE PLATE, AND AN OVERHANGING SHROUD OUT-TURNED AT RIGHT ANGLES TO THE VANE AT THE OUTER EDGE THEREOF AND INCLINED AT A COMPRESSION ANGLE TO THE PLANE OF THE PLATE, SAID SHROUD DEFINING WITH SAID VANE AND THE OPPOSING REGION OF THE PLATE AN ELONGATE PASSAGE DEVIATING FROM THE DIRECTION OF ROTARY MOVEMENT AND REDUCING FROM THE INLET TO THE OUTLET, WHEREBY THE COMPRESSION UNIT ACCELERATES THE AMBIENT MATERIAL TO BE MIXED BOTH BY PUMPING AND BY COMPRESSING SAID MATERIAL SUBJECT TO SAID PASSAGE AND CAUSING IT TO DISCHARGE FROM THE PASSAGE OUTLET AT RELATIVELY HIGH VELOCITY AND SO AS TO IMPINGE UPON THE ENCOMPASSING MATERIAL WITH A VOILET SHEAR AND AUGMENTED DISPERSING ACTION. 